IV DoseAny IV dose should be 75% of corresponding oral dose (see below)
Oral doseDosing guidelines are largely a theological issue among pediatric cardiologists.
Total oral digitalizing dose (TDD) given over 24 hours:
Prematures: 20 ug/kg
Full term newborns: 30 ug/kg
Infants < 2years: 40-50 ug/kg
Children >2 years: 30-40 ug/kg
Adults: 1.25-1.5 mg total dose.
Maintenance: 25% of TDD, daily divided BID.
LevelsLife is too short to argue about whether digoxin levels are meaningful, other than in suspected toxicity.
Column-separated levels in infants.
O.7-2.0 nanograms/ml in adults.
Levels up to 3.5 are well tolerated in infants
KineticsInfants and children have high volumes of distribution.
Elimination half-life by age:
Prematures: 61 hours.
Full term newborns: 35 hours
Infants: 18 hours.
Children: 37 hours.
Adults: 35-48 hours.
CautionsMost common arrhythmias due to toxicity are PVCs and VT in adults, PAT with block in children
InteractionsLevels increased by erythromycin, quinidine, amiodarone, verapamil and aldactone. (!) Levels decreased by phenytoin. Digoxin toxic arrhythmias exacerbated by bretylium due to initial catechol release from nerve terminals
PreparationsLanoxin scored tablets: 0.125, 0.250. 0.500 mg
Lanoxicaps (solution in capsule): 50, 100, 200 ug.
Lanoxin elixir (60 cc dropper bottle): 50 ug/ml.
Lanoxin injection, Adult: 500 ug/2 ml
Pediatric:100 ug/1 ml
FDA approval in childrenOne of the few!